Adiponectin and Hypertension in Normal-Weight and Obese Children

Abstract

BACKGROUND: Adiponectin (AD) reduces the risk of hypertension because of its anti-inflammatory, antiatherogenic, and insulin-sensitizing properties. The study described here was done to evaluate the interrelationships of AD, blood pressure (BP), obesity, body-fat distribution, puberty, and insulin resistance in a selected group of children. METHODS: The study was a cross-sectional, observational study of 186 children ranging in age from 5-18 years and grouped according to weight class (obese (OB), n = 100; normal weight (NW), n = 86) and BP category (hypertensive (HT) n = 79; normotensive (NT); n = 107). The children were also classified on the basis of fat distribution (waist circumference/height ratio). Their blood glucose, insulin, and AD concentrations were assayed, and their homeostatic model assessment (HOMA) index was calculated as an estimate of insulin resistance. RESULTS: Serum AD was lower in OB-HT (7,111±4,163ng/ml) than in NW-NT (12,622±6,276ng/ml) children (P < 0.0001). Intermediate values of AD were found in OB-NT (9,099±3,988ng/ml) and NW-HT (9,808±4,211ng/ml) children. Weight and waist circumference-to-height ratio, BP category, and pubertal stage were all independently and inversely associated with serum levels of AD (P < 0.02). In a logistic regression model, after adjustment for body mass index (BMI) and waist circumference/height ratio, serum levels of AD maintained an independent association with hypertension (P < 0.05), as did also the HOMA index (P < 0.05). A reduction of 10 times (i.e., one unit on the log(10) scale) in AD serum levels was associated with a 50% increased probability of having hypertension. CONCLUSIONS: In childhood, serum levels of AD are inversely related to hypertension. This relationship is partly independent of obesity, fat distribution, and insulin resistance. Low values of AD in both OB and NW children are associated with a higher probability of hypertension.